Instead of only selecting one widget at a time in dashboard edit mode, you also have the possibility to select multiple widgets. Changing a setting in the widget tab will then change the setting in every selected widget.
Currently, this only works for enabling/disabling dashboard filters and enabling/disabling warning symbols (if all your selected widgets support this setting).
Selecting multiple widgets
If you have already selected a single widget (indicated by a blue border around the widget) you can hold the Ctrl key (command on Mac) on your keyboard and click on any other widget, and it will be added to the selection.
If everything worked, you should now have two widgets with blue borders. When you look at the widget tab in the right sidebar now, you should see a small message telling you how many widgets you have selected, as well as some settings that you can now change for all your selected widgets.
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Removing widget from selection
If you have multiple widgets selected and want to remove a widget from your selection, simply Ctrl + click on the selected widget again, and it will be removed from your selection.